Bridging structures



Oct. 10, 1961 M. F. SMITH 3,003,167

BRIDGING STRUCTURES Filed Oct. 50, 1958 3 Sheets-Sheet l INVENTOR.

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Oct. 10, 1961 M. F. SMITH BRIDGING STRUCTURES Filed oct. so; 195e 3Sheets-Sheet 2 INVENTO?. Mr/3121751771177, BY

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Oct. 10, 1961 M. F. sMlTH 3,003,167

BRIDGING STRUCTURES Filed Oct. 50, 1958 3 Sheets-Sheet 3 life /Ijgc JBZ13a A BWM/y @auf A TTORNE YS.

3,003,167 BRIDGING STRUCTURES Marion F. Smith, Philadelphia, Pa.,assignor to Dodge Steel Company, Philadelphia, Pa., a corporation ofPennsylvania Filed Oct. 30, 1958, Ser. No. 770,787 4 Claims. (Cl. 14-71)This invention relates to bridging structures. More particularly, it isconcerned with bridging structures of a kind in which a spanning elementpermanently connected to a platform is movable from a normally retractedposition on the platform to span an interval between said platform andanother platform either of a mobile or stationary type.

The chief aim of my invention is to provide a simple and inexpensivebridging structure of the kind referred to, wherein the spanning elementis easily and quickly extended from its normal retracted position on theone platform into bridging relation with the other platform, andsimultaneously upwardly tilted and nally lowered to bridging position.

In connection with a bridging structure having the above mentionedattributes, it is a further aim of my invention to provide simple stopand locking means by which the spanning element is securable againstaccidental displacement in either its normally retracted position, or inits extended position bridging the interval between the two platforms.

As will be readily evident from subsequent disclosure hereinafter, thebridging structure of my invention is adaptable for' use in bridging theclearance interval between the platforms of two coupled flat top railwaycars, between the deck of a boat or ship and a pier or dock, or betweenthe floor of a delivery truck and a loading or unloading platform.

Other objects and attendant advantages will appear from the followingdetailed description wherein:

FIG. 1 is a fragmentary view in top plan showing two platforms of whichthe confronting ends are spaced by an interval, and a spanning elementconveniently embodying my invention as associated with one of theplatforms and shown in its normal `retracted condition.

FIG. 2 is a View similar to FIG. 1 showing the structure extended tospan the interval between the two platforms.

FIG. 3 is a fragmentary view in elevation looking as indicated by theangled arrows III-III in FIG. 2.

FIG. 4 is a fragmentary view in cross section drawn to a larger scaleand taken as indicated by the angled arrows IV-IV in FIGS. 2 and 3.

FIG. 5 is a fragmentary view in elevation of the right end portion ofFIG. 3 drawn to a larger scale.

FIG. 6 is a detail view in elevation on `a larger scale looking asindicated by the angled arrows VI-VI in FIG. 2.

FIGS. 7-11 are diagrammatic views showing successive positions of a cammember included in the bridging structure.

With more specific reference iirst to FIGS. 1-4 of these illustrations,the numerals 1 and 2 respectively designate two platforms of vwhich thecontiguous ends are spaced by an interval 3. As exemplified in FIGS. 3and 4 the platform 1 is shown as having a foundation frame 4 which maybe of structural steel.

' The bridging structure with which the present invention is moreespecially concerned comprises a spanning element 5. As shown, thisspanning element 5 is a rectangular oblong in configuration and has atop surface 6 of stout plate metal which is upwardly arched in thedirection of its length and to which are welded at the bot- StatesPatent rice tom and adjacent its longer side edges 6a and 6b, invert Tsection reinforcing bars 7 and 8. Also welded to the bottom of theelement 5 along its longitudinal center is an invert T sectionreinforcing bar 9. Similarly integrated with the plate 6 at the bottomare two laterallyspaced transverse angle section reinforcing bars 1t)and 11 and a curved cam bar 12 fashioned from invert T section material,the transverse bar 11B extending between and being integrated with thelongitudinal bars 7 and 8. The transverse reinforcing bar 11 extendsbetween and is integrated 'with the longitudinal and center bars 9 and8, and the cam bar `12 is arranged beneath and welded to the bottom ofsaid plate 6 across one corner thereof. The upright lianges of the bars7, 8 and 9, and the cam bar 12 have their top edges curved, as best seenin FIGS. 3 and 7-11, to archedly support the top plate 6 of the spanning element 5. At the rear corner occupied by the cam bar 12, theelement 5 has a horizontal axis pin 15 which passes through a bracket15a and through the head 16 at the top of a pendent vertical axis swivelbolt 17 rotatively engaged in a bearing 18 tixedly set into the metallicunderframe 4 of the platform 1 as shown in FIG. 4, the cam bar beingcurved on an arc struck from the axis of said bolt. Pin 20a passesthrough bracket 20h and supports roller 2t) at the immediately adjacentcorner of the element 5. As a consequence of this construction, it willbe seen that the element 5 can be swung outwardly about the verticalaxis swivel bolt 17 from a retracted position on the platform 1 to thebridging position of FIG. 2 and will be at the same time tilted bymovement upwardlyr about the horizontal pivots 15 and 20a so that itsswinging end will clear the top of platform 2 until the element 5 isfully moved to bridging position. Somewhat inwardly of the longitudinalreinforcing bar S the element 5 is provided at the bottom at the corner,in the direction of the edge 6C remote from the corner occupied by theswivel bolt 17, with a roller 20 which is adapted to travel over acurved metallic track 21 set into the top of platform 1 in concentricrelation to the axis of said bolt 17. Normally, the element 5 ispositioned as shown in FIG. 1 crosswise of the platform 1 and whollywithin the end portion of the latter with the edge 6c engaged, at thecorner at a point adjacent the edge 6b, with a stop lug 22 upstandingfrom the platform. A similar lug 23 is provided on the platform 1 forengagement by the edge 6a to serve as a stop for limiting the outwardswing of element 5 as shown in FIG. 2.

Welded to the end of the underframing 4 of the platform 1 is a socket 25for reception of a removable locking pin 25 (FIGS. l, 2 'and 6) which,in cooperation with the side edge 6a, serves as `a locking means toprevent displacement of the element 5 when it is in the retractedposition of FIG. r1, and also in cooperation with the side edge 6b whenit is in extended position as in FIG. 2. To insure lagainst loss of thepin 26, it is attached, by a flexible element in 'the form of a chain27, to the underframing 4 of the platform 1 at 28. Also, Ialiixed to thefront end of the underframing 4 of the platform 1 is a bracket 30 for aroher 31 over which the arcuate cam bar 12` is adapted to ride when theelement 5 is being moved.

By reference to FIGS. 7-11 it will be noted that the `bottom surface atIthe leading end of the arcuate cam bar 12 is inclined downwardly andoutwardly from one end at Ia slight angle to the horizontal as at 12a tomeet with a straight horizontal mid-portion 12b, and that outwardlyybeyond said straight mid-portion 412b said edge is sloped upwardly at asomewhat sharper angle as at 12C to a depressed portion 12d, andthereafter slopes downwardly land outwardly at 4a gentler angle to thehorizontal as at 12e to the opposite or outer end of said cam bar.

Operation In preparation for moving the spanning element from thenormally retracted idle position of FIG. 1 to the bridging position ofFIG. 2, the locking pin 26 is first withdrawn from its socket 25. Withthe element 5 now free, it is swung outwardly about the swivel bolt 17as ian axis, and `as the bottom edge portion 12a of cam bar 12 rides theroller 31, the spanning element 5 is gradually lifted and by the `timethe bottom edge portion 12b of said cam bar reaches `said roller, theleading outer corner portion of element 5 is raised to a level clear ofthe top of the platform 2 when element 5' reaches the position indicatedin broken lines yat A in FIG. 1. As the bottom edge portion 12b of cambar 12 later overtravelsl the roller 31, the leading corner of theelement 5 is held at the aforesaid level until it reaches the positionindicated in broken lines lat B in FiG. l with said corner overhangingthe platform 2. Then as the element 5 is further swung and the slope 12eof the cam bar 12 rides the roller 31 as in FIG. 10, the element 5 is'lowered rather rapidly and the edge portion 6a is let down into slidingengagement with the top of the platform 2. In its further movement, theelement 5 is finally arrested in bridging position by engagement of itsside edge 6a with the stop lug 23 on the platform 1 with the notch 12dbetween the sloping edge portions 12C and 12e of the cam bar registeredwith but free of contact with the said roller as in FIG. 11. In order topermit the `swinging end portion of the element 5 to rest firmly uponthe platform 2 `and relieve roller 20 of any load responsibility when inbridging position, an opening 35 (FIGS. 2 and 4) has been provided inthe top of the platform 1 into which the roller 20 can recede. With theelement 5 now fully moved to bridging position, the bolt 25 is replacedin its socket 26 to lock the element against displacement. ln the returnswing of the element 5 it is tilted upwardly about the horizontal pivotaxis as the edge portion 12C of the cam bar 12 overrides the roller 31and is so held for a time with the end edge 6d of said element 5 clearof the top of the platform 2. As the return swing of the element 5continues, said element is gradually let down as the edge portion 12a ofthe cam bar 12 overrides the roller 31 incident to which the roller 20is lbrought into engagement with the track plate 21. After the spamiingelement S has been swung to fully retracted position with the edge 6cthereof stopped by the lug 22 on the platform 1 `as in FIG. l, the pin26 is re-inserted into the socket to `lock said element in place. Tofacilitate the above described manipulation of element 5 it is providedat the corner regions of its swinging end portion with apertures 36 intowhich a hook at the end of a pull `rod can be selectively engaged. Dueto the provisions made for upwardly tilting the element 5 as the outwardswing is initiated, my improved bridging `structure will adapt itselffor use with platforms 2 which may differ in level from that of theplatform 1, as will be 'evident from the broken line showings in FIG. 3.

While in accordance with the provisions of the statutes, I haveillustrated land described the best form of embodiment of my inventionnow known to -me it will be apparent to those skilled in the art thatchanges may be made in the form of the apparatus described withoutdeparting from the spirit and scope of the invention, as set forth inthe appended claims, and ythat in some cases certain vfeatures of myinvention may be used to advantage without a corresponding use of votherfeatures.

Having thus described my invention, yI claim:

1. A bridging structure spanning an interval between the confrontingends of two platforms, said structure comprising a substantially flatpolygonal spanning element 4 adapted to normally rest in retractedposition upon one of the platforms; a swivel bolt pendently connected atits upper end by a horizontal pivot pin to the underside of the spanningelement at one rear corner thereof; a vertical axis socket bearing forsaid bolt secured to said one platform; means for restraining the swivelbolt against axial movement in the socket bearing; a cam bar afiixed tothe under face of the spanning element and curved on an arc centered inthe axis of the swivel bolt, said cam bar having along the bottomthereof, -a cam surface portion sloped downwardly and outwardly from theleading end of the bar and meeting with the horizont-a1 intermediatepoition, a portion sloping upwardly and outwardly from the horizontalportion to a depressed portion, and a downwardly and `outwardly slopingportion beyond said depressed portion; and a roller for cooperation withthe cam bar journaled in a bracket secured to the outer edge of said oneplatform at a distance substantially equal to the radius of said cam barwhereby, as the spanning element is swung outward from normallyretracted position crosswise `of said one platform about the swivel boltand the upwardly inclined portion of the same surface of the trackoverrides said roller, the spanning element is first tilted upwardslightly about the horizontal pin aforesaid to bring its distal endabove the level of the other platform and then so held for a time as theintermediate level portion of the cam bar overrides said roller; andwhereby upon approach of said element to bridging position, it isgradually let down until its distal end finally bears upon said otherplatform as the depressed portion of the cam bar overrides said roller,and vice versa.

2. A bridging structure characterized as in claim 1, further including aroller supported from the underside of the spanning element at the otherrear corner thereof; and an arcuate track for said roller, said trackbeing curved on `an arc having its center in said swivel bolt and beingsecured upon the top Of said one platform.

3. A bridging structure characterized as in claim 1, further including apair of stop abutments secured at spaced intervals upon said oneplatform, one abutment for limiting the outward swing of the spanningelement and the other `abutment for limiting the inward or return swingof the spanning element.

4. A `bridging structure characterized as in claim l, further includinga vertical axis socket member affixed to the outer edge of said oneplatform iat a distance from the axis of the swivel bolt equal to thewidth of the spanning element, and 'a retractable stop pin engageableinto said socket member for locking the spanning element againstaccidental displacement either in normal retracted position on the saidone platform, or in bridging position.

References Cited in the tile of this patent UNITED STATES PATENTS 33,606Selser Oct. 29, 1861 214,530 Snyder Apr. 22, 1879 602,460 Mason Apr. 19,1898 2,188,554 Marianne Jan. 30, 1940 2,329,855 Ryder Sept.'21, 19432,372,574 Haynes Mar. 27, 1945 2,602,944 Richardson July 15, 19522,617,131 Harris Nov. 11, 1952 2,641,785 Pitts et al June 16, 19532,817,102 Harris Dec. 24, 1957 FOREIGN PATENTS 14,158 Sweden July 9,1901

